• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.239-242
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• 2003

Transmit diversity using STBC(Space Time Block Code) provides the same diversity gain as MRRC(Maximal Ratio Receiver Combining), when the fading channel is constant across two consecutive symbols. But, when the channel condition is changed for the two consecutive symbols, the transmit diversity using STBC does not offer good performance due to the large doppler shift. In this paper, we have proposed a interference cancellation scheme for performance enhancement in transmit diversity using STBC over time selective fading channel. Simulation results for various doppler shift rates are presented for the transmit diversity using the proposed scheme.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1331-1336
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• 2008

This paper suggests a method using Bayesian inference to estimate the parameters of Weibull distribution and acceleration parameters under the condition that the stresses are time-dependent functions. A Bayesian model based on the discrete time approximation is formulated to infer the parameters of interest from the failure data of the virtual tests and a statistical analysis is considered to decide the most probable mean values of the parameters for reasoning of the failure data.

• 소음진동
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• 제9권6호
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• pp.1240-1246
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• 1999

A prior error estimator which is solving structural dynamic problems and which is based on the generalized-method, is developed. Since the proposed error estimator is computed with only previous information, the time step size can be adaptively selected without the feedback mechanism. This paper shows that the automatic time stepping algorithm using the error estimator performs an efficient time integration. To verify its efficiency, several examples are numerically investigated.

• 디지털산업정보학회논문지
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• 제11권1호
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• pp.97-109
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• 2015

In this paper, we design and implement a two-way automatic communication system using a mobile instant messenger that can provide a customized service through a real-time two-way communication using a mobile instant messaging service. Two-way automatic communication system using a mobile instant messenger can improve the quality and quantity of information in real-time update of the information through the feedback. In addition, since it is communicated by using a mobile Instant Messanger in 1:1 there is no concerns that is recognized as spam, as well as it is possible to provide customized information for each user. Two-way automatic communication system using a mobile instant messanger shows the difference of the speed according to the data input time in typing by hands in result of comparing the time to input a date and the processing speed to search a data. Therefore in category treatment, command processing and natural language processing, Category treatment way is the most excellent in aspect of data processing speed, otherwise in aspect of the total speed to combine the data input time and the processing time, the command processing way is the best method.

• 한국게임학회 논문지
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• 제1권1호
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• pp.17-23
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• 2001

본 논문에서는 게임의 긍정적인 효과와 부정적인 효과에 대하여 알아보고, 최근 게임의 묘미와 교육적 효과를 동시에 강조하는 에듀테인먼트 인터넷 게임의 경향에 대하여 살펴본다. 그런데 기존의 교육용 게임들은 그 흥미도가 낮아 잘 사용하지 않으려는 경향이 있는 반면 시뮬레이션 게임이나 롤플레잉게임 등 흥미위주의 게임은 그 중독성이 매우 강하므로, 컴퓨터 에서 게임사용을 제한하고 유익한 목적의 컴퓨터사용을 활성화 할 필요가 있다. 따라서, 교육용 컨텐츠를 활성화하고 게임중독을 치료하기 위한 동적 컴퓨터 사용시간 제어시스템 (dynamic computer using-time control system)의 모델을 제시한다. 본 논문에서 제시하는 방법은 기존의 정량적인 컴퓨터 사용시간 제한 프로그램과는 달리 사용자의 교육용 프로그램이나 교육용 컨텐츠의 사용에 비례해서 컴퓨터 사용시간을 증가시키는 동적 제어시스템으로 사용자가 자발적으로 교육용 프로그램이나 교육용 컨텐츠를 이용하도록 유도한다.

• 제어로봇시스템학회논문지
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• 제18권11호
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• pp.1040-1044
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• 2012

We design a NCS (Networked Control System) where the communication between sensors and controllers takes place over a USN (Ubiquitous Sensor Network). In order to measure time delays between sensors and controllers in real time, we design an algorithm to measure RTT (Round Trip Time) between USN nodes, and implement it into TinyOS of USN. By using the measured time delays, we construct the Smith predictor to compensate the time delays between sensors and controllers in real-time. For the real time experiment, we simulate the dynamic plant model, controller, and USN interface using Real-Time Windows Target provided in MATLAB. The USN interface in the Simulink model consists of serial ports, which connect the plant output and controller with USN nodes. The experiment results show that the time delays between sensors and controllers are precisely measured in real time; the Smith predictor appropriately compensates the time delays; and the stability is achieved in the closed-loop of the NCS.

• International journal of advanced smart convergence
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• 제9권1호
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• pp.109-112
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• 2020

Many devices are connected on the internet to give functionalities for interconnected services. In 2020', The number of devices connected to the internet will be reached 5.8 billion. Moreover, many connected service provider such as Google and Amazon, suggests edge computing and mesh networks to cope with this situation which the many devices completely connected on their networks. This paper introduces the current state of the introduction of the wireless mesh network and edge cloud in order to efficiently manage a large number of nodes in the exploding Internet of Things (IoT) network and introduces the existing Network Time Protocol (NTP). On the basis of this, we propose a relatively accurate time synchronization method, especially in heterogeneous mesh networks. Using this NTP, multiple time coordinators can be placed in a mesh network to find the delay error using the average delay time and the delay time of the time coordinator. Therefore, accurate time can be synchronized when implementing IoT, remote metering, and real-time media streaming using IoT mesh network.

• 대한가정학회지
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• 제31권3호
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• pp.1-13
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• 1993

This study examined the expenditure on time-saving services and related variables. The time-saving services are food away from home, delivery food, dry cleaning, clothing care, helper and total service. The specific objectives of this study were: (1) to investigate the differences in the expenditure on time saving services according to social economic and demographic variables. (2) to investigate the differences in the expenditure on time-saving services according to role-overload, home goal orientation and work goal orientation. (3) to investigate the independent influence of variables related to the expenditure on time-saving services. For this objectives survey was conducted using interview. The data used in this study included 160 women living in Seoul from employed professional housewives, employed non-professional housewives and non-employed housewives. Statistical analyses were conducted using frequencies, percentiles, mean, oneway ANOVA, DUNCAN-test and multiple regression. The major findings were: (1) Wife's education, wife's age, income, tenure, level of living and employment status were significantly related to the expenditure on time-saving services by using the one-way ANOVA. (2) Income, education, level of living, number of children, and employment status explained the variance of the expenditures on time-saving services about 20%-39% by using a multiple regression method.

• 가정간호학회지
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• 제15권1호
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• pp.22-28
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• 2008

Purpose: The aim of this study was to analyze the effects of time management on the clinical nurse's organizational commitment and job satisfaction. Methods: Subjects were recruited in two general hospitals in Seoul and Incheon. Data collection was done using a self-report questionnaire. Time management was measured using the questionnaire developed by Han (1992). Organizational commitment and job satisfaction were measured using the questionnaire developed by Yoon (2000), based on Mowday et al. (1979) and Stamps et al. (1978). The data were analyzed using the SAS statistical package program, version 10.0. Specifically, descriptive statistics and stepwise multiple regression were performed. Results: The predictive time management factors for organizational commitment included deadline decision, simplification, and goal-setting. The predictive time management factors for job satisfaction included planning/making the priority order, deadline decision, simplification, asking for help, and responsibility reduction. Conclusion: Time management factors are highly correlated with organizational commitment and job satisfaction in clinical nurses. Deadline decision and simplification are common predictive factors for organizational commitment and job satisfaction. These results can be used to develop more effective time management strategies for increasing organizational effectiveness in clinical nurses.

• 대한영양사협회학술지
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• 제26권2호
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• pp.126-140
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• 2020

The purpose of this study was to investigate the association between dietary quality and smart device use among middle school students. A total of 330 middle school students (171 boys and 159 girls) residing in Incheon participated in this questionnaire survey in June 2018. The boys and girls were divided into two groups according to their daily use time of smart devices: less than 3 hours a day (<3 hours) and 3 hours or more a day (≥3 hours). Eating habits and dietary quality were assessed using a nutrition quotient for adolescents (NA-Q). For boys and girls, higher consumption frequency of white milk was significantly associated with less time spent using a smart device. For boys, a higher number of vegetable dishes and eating frequency of breakfast were significantly associated with the less time spent using a smart device. For girls, higher consumption frequency of processed beverages, ramyeon, and street foods was significantly associated with more time spent using a smart device. For boys and girls, those who spent more time using a smart device had significantly lower NA-Q scores, indicating low dietary quality. To sum up, more time spent using a smart device among middle school students may be associated with lower dietary quality. These results suggest the need to provide a nutrition education program and guidelines to students who use smart devices for a long time.